A medical tube has been used in very many medical devices such as an infusion set for administration of infusion fluid from infusion bag, a transfusion set used in the same manner as above for the transfusion, a blood bag used for collection of blood from humans such as blood donation and circuits used in the application of blood dialysis, cardiopulmonary bypass, etc.
Up to now, polyurethane resin, silicone resin and vinyl chloride resin have been commonly used as a material for molding a medical tube. A medical tube comprising polyurethane resin has some hardness and, when it is pushed or revolved, the resulting force is apt to be transmitted to the front end whereby it exhibits good operating property and also softening property by body temperature. In the case of a medical tube comprising silicone resin, although it is flexible, it is too soft whereby its operating property is inferior. A medical tube comprising vinyl chloride resin has such characteristics that its molding property is good, its material cost and production cost are less expensive, its soft property as a tube is adequate and its processing property in assembling a medical device, etc. is good.
A technique has been also known wherein adaptability to blood is improved by immobilization of heparin on the surface contacting the blood (Refer, for example, to Patent Document 1). According to said document, a surface treatment is as follows: an ionic compound of hydrophobic organic cation mixture with hydrophilic heparin is firstly produced, dissolved in an organic solvent such as tetrahydrofuran and applied onto the surface of a medical device and, after that, the organic solvent is removed by means of drying with aeration. Although it is possible to just apply onto the surface of a medical device by such a method, there have been problems of appearance defect therein such as occurrence of turbidity (aggregation of the ionic compound) and oil defect (elution of a plasticizer) on the surface of a tube.